THE TONGUE. 



1127 



papilla is composed of a conical projection of the corium, covered with microscopic 

 papillae like those of the skin, and covered by a thick long cap of stratified squamous 

 epithelium. 



In many of them the cap of epithelium is broken up into several long slender hair-like 

 processes, giving rise to the variety known as filiform papillae. The cap of epithelium is 

 being constantly shed and renewed, and an excessive or diminished rate of shedding or 

 renewal, coupled with the presence of various fungi, gives rise to the several varieties of 

 " tongue " found in different diseases. 



The conical papilla are longer and larger than the filiform, and have a wider base. 

 They are situated on the dorsum among the filiform papilla?, and resemble them in their 

 structure. 



The conical and filiform papillae are probably of a prehensible or tactile nature, and 

 are highly developed, and horny, in carnivora. 



The fungiform and lenticular papillae (Fig. 890) are larger and redder, but less 

 numerous than the first variety, and they are found chiefly near the tip and 

 margins of the tongue, comparatively few being present over the dorsum generally. 



Epith 



Tast( 



Serous gland 

 elium covering | 

 papilla of corium 



Vallum around 



papilla 

 Epithelium of 



summit of ; 

 vallate papilla 



Loose epithelium on 

 surface of papilla conica 



Stratifli 

 thelial 



Iepi- 

 p Connective tissue 

 corium < 



,; -'.' *. 



; - :* 





' "ft^ ' ! 



m 





(ilamlula lingualis 



mm 



Blood-vest 



A FIG. 891. 



A. Section of a papilla vallaf a of tongue. B. Section of papillse conicae of tongue. 



Each is in shape like a " puff-ball " fungus, consisting of an enlarged rounded head, 

 attached by a somewhat narrower base. As in the case of the conical papillae, the 

 corium is studded over with microscopic papillae, which are buried in the covering 



1 of squamous epithelium and do not appear on the surface. Most of the fungiform 

 papillae, if not all, appear to be furnished with taste-buds, and they are probably 



, intimately connected with the sense of taste. The lenticular papillae are placed on 

 the margin of the tongue. They are flatter than the fungiform papillae, and do 

 not contain taste-buds. 



The vallate papillae (O.T. circumvallate) (Fig. 891), much the largest of all the 

 papillae of the tongue, are confined to the region immediately in front of the sulcus 

 terminalis and foramen caecum. Usually about nine to fourteen in number, they 

 are arranged in the form of the letter V, with the apex posteriorly, just in front 

 of and parallel to the sulcus terminalis. One or two of the papillae are usually 

 placed at the apex of the V, immediately anterior to the foramen caecum. In appear- 

 ance a vallate papilla resembles very closely the impression left by the barrel 

 of a small pen pressed on soft wax (Fig. 891). Each is composed of a cylindrical 



72 1 



